1. Field of the Invention
The present invention relates to a liquid crystal display device provided with a photo-alignment film, and more particularly to a high-definition and high-contrast liquid crystal display device with a high aperture ratio.
2. Description of the Related Art
Regarding liquid crystal display devices, in order to achieve a wide viewing angle, liquid crystal display devices of horizontal electric field types such as an in-plane switching (IPS) type and a fringe field switching (FSS) type have been developed. A liquid crystal display device of a horizontal electric field type controls the backlight intensity and displays an image by applying an electric field in a direction parallel to a substrate and rotating liquid crystal molecules in a horizontal plane in a state in which the liquid crystal molecules are horizontally aligned or in a homogeneous alignment state.
In addition, for a liquid crystal display element, a photo-alignment method has been proposed as a processing method for adding an aligning ability to a liquid crystal alignment film. The photo-alignment method is characterized by irradiating a polymer film containing photoisomerizable compounds such as azo dyes with linearly polarized ultraviolet light (polarized UV light) or the like, causing a photoisomerizable compound oriented in a polarization direction or a polymer chain to selectively react, further causing anisotropy in alignment of molecules of the polymer film, thereby obtaining the liquid crystal aligning ability.
As a liquid crystal display device of the horizontal electric field type provided with a photo-alignment film, JP-A-2012-113212 discloses an IPS type or FSS type liquid crystal display device that has a frustum-shaped spacer formed on an opposing substrate and has a photo-alignment film formed therein.
In addition, JP-A-H11-174462 discloses a liquid crystal display device of a horizontal electric field driving type without a photo-alignment film, in which columnar insulating films (columnar spacers) having a side surface with a cross-sectional shape parallel to a rubbing direction are located at each intersection of electrode wirings arranged in a matrix form (refer to Abstract of JP-A-H11-174462).